The reaction and regeneration behavior of melamine (MN)

a kind of solid organic amine

with SO2 was studied. The results show that MN desulfurization rate is above 99% for 140 min at simulated flue gas:0.35%SO2+ 5%O2 + N2

40℃ and 4% MN (mass fraction). Meanwhile

the breakthrough sulfur capacity (200 mg/m3 SO2 in outlet flue gas) is 0.33g SO2/(g MN). The analysis of MN desulfurization and regeneration products by XRD

FTIR

SEM and TG-MS shows that MN reacts with SO2 to produce melamine sulfite firstly

and then melamine sulfite is oxidized to melamine sulfate partly by oxygen in the flue gas. Adding 0.1% p-diphenylamine can effectively inhibit the melamine sulfite to be oxidized. Melamine sulfite can be heated and regenerated in 75-150℃

but the melamine sulfate cannot be regenerated by heating. The oxidation rate of melamine sulfite decreased from 36% at 5%O2 to 13% at 5%O2+ 0.1% p-diphenylamine. When products were heated at 150℃ for 2 h desulfurization

the regeneration rate of melamine increased from 58% at 5%O2 to 94% at 5%O2+ 0.1% p-diphenylamine. MN has excellent desulfurization and regeneration performance in the anti-oxidation mode.